Diabetes management system and method for controlling blood glucose

ABSTRACT

A diabetes management system for predicting a future blood glucose value of a patient and for recommending a corrective action to the patient when the future blood glucose value lies outside of a target range. The system includes a patient-operated apparatus for measuring blood glucose values and for storing data relating to insulin doses administered to the patient. The apparatus predicts the patient&#39;s future blood glucose value based upon the patient&#39;s current blood glucose value, the fraction of insulin action remaining from the insulin doses, and the patient&#39;s insulin sensitivity. The apparatus also determines the corrective action for the patient when the predicted blood glucose value lies outside of a target range. The system also includes a physician computer in communication with the apparatus for receiving the blood glucose values and insulin dose data and for calculating an adjusted insulin sensitivity for use in subsequent predictions.

CONTINUATION APPLICATION INFORMATION

This application is a continuation in part of application Ser. No.08/781,278 filed Jan. 10, 1997, now U.S. Pat. No. 5,956,501 which ishereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates generally to disease management systems,and in particular to a diabetes management system for predicting afuture blood glucose value of a patient and for recommending acorrective action to the patient when the future blood glucose valuelies outside of a target range.

DESCRIPTION OF PRIOR ART

Insulin dependent diabetes mellitus (IDDM) is caused by the auto-immunedestruction of the insulin producing islets of Langerhans in thepancreas. Insulin replacement therapy is the interim treatment for IDDMuntil such time as islet transplants become feasible. Insulin lowers theconcentration of glucose in the blood, while food raises theconcentration of glucose in the blood. The challenge of insulin therapyis to administer food and insulin in a manner which maintains bloodglucose concentrations in an acceptable range, thereby avoidinghypoglycemia and hyperglycemia.

Hyperglycemia has adverse long term consequences for the body. Theseconsequences include kidney damage leading to kidney failure,micro-enurisms in the retina causing blindness, and the blocking ofcapillaries in the extremities causing an inability to heal wounds andsubsequent gangrene. Hypoglycemia has an immediate adverse consequenceof reduced brain function which leads to confusion and an inability toreason, remember, or react. In the extreme, hypoglycemia causes seizure,coma, and death.

The first insulin used by diabetes patients was regular insulin takenfrom beef or pig pancreases. This insulin lasts for about six hours, sothat patients were required to inject it three or four times per day.After World War II, longer acting insulin was developed by bindingregular insulin to protamine and zinc. Regular insulin dissociatesslowly from protamine and zinc, extending insulin action to twelve hoursfor intermediate acting insulin and twenty-four hours for ultra-lenteinsulin. Patients enjoyed reducing injections to one per day, but wererequired to modify their eating to a snack-all-day regimen to avoidhypoglycemia. The one daily insulin dose was adjusted as needed toreduce the incidence of both hypoglycemia and hyperglycemia.

The development of portable blood glucose meters encouraged thedevelopment of more sophisticated insulin therapy regimens. One of theseregimens is the split/mixed regimen which consists of two daily doses ofmixed regular and intermediate acting insulins taken before breakfastand dinner. These four insulin therapy components are adjusted usingblood glucose values measured before each meal and at bedtime. Patientsusing the split/mixed regimen are required to eat substantially the samemeals every day so that the four insulin components may be adapted tothe consistent meal pattern over time.

The split/mixed regimen has the advantage of allowing independentadjustment of insulin doses for each meal and requires only twoinjections per day. However, it has several disadvantages which areprimarily due to the intermediate acting insulin components. Theintermediate acting insulin taken before breakfast affects lunch timeand pre-dinner blood glucose, requiring a patient to commit to the sizeand timing of lunch before eating breakfast. The broad action of theintermediate acting insulin may lead to hypoglycemia before or afterlunch when the size or timing of the lunch is varied. Similarly, theintermediate acting insulin taken before dinner requires the patient toeat a snack at bedtime to mitigate nocturnal hypoglycemia. Even when asnack is eaten, the intermediate acting insulin may cause hypoglycemiaaround 3 AM when its action peaks.

Many of the disadvantages of the split/mixed regimen are overcome in asecond insulin therapy regimen called the basal/bolus regimen. Thebasal/bolus regimen attempts to emulate the method by which an intactpancreas controls blood glucose. Normally, the intact pancreas producesa steady supply of basal insulin to accommodate the body's basic restingneeds. The pancreas handles meals by releasing a sharp impulse of bolusinsulin in a first phase. The sharp impulse of bolus insulin raisescirculating insulin levels immediately. The first phase is followed by asustained level of heightened insulin release in a second phase. Thesecond phase continues until the body's blood glucose concentrationfalls back to normal, at which point basal levels are obtained onceagain.

In the basal/bolus regimen, the basal insulin releases are emulated bytwo daily basal injections of intermediate acting insulin, such as Lenteor Neutral Protamine Hagedorn (NPH), generally taken before breakfastand at bedtime. The bolus insulin releases are emulated by bolusinjections of regular or fast acting lispro insulin taken before eachmeal. Fast acting lispro insulin allows the bolus injections to emulatethe first phase action of the pancreas better than regular insulin byreducing the delay before the insulin injection takes effect and byshortening the overall duration of the insulin's action.

Thus, the basal/bolus regimen generally includes four insulin doses perday consisting of a pre-breakfast dose of intermediate insulin combinedwith regular or lispro insulin, pre-lunch and pre-dinner doses ofregular or lispro insulin, and a bedtime dose of intermediate insulin.The two basal insulin doses accommodate the basic insulin needs of apatient absent any perturbations due to food. Food is handled by thebolus insulin doses, which the patient attempts to tailor to the amountof food to be eaten.

Problems arise in the basal/bolus regimen when a patient incorrectlyestimates the dose of bolus insulin required for a given meal. Toolittle insulin causes the patient to develop hyperglycemia, while toomuch insulin causes the patient to develop hypoglycemia. Hypoglycemia orhyperglycemia may also result when the size of the meal is variedwithout adequate adjustment of the bolus insulin dose. Patients usingthe basal/bolus regimen are typically required to eat substantially thesame meals every day so that the bolus insulin doses may be adapted tothe consistent meal pattern over time.

Several electronic diabetes management systems have been developed toassist patients in the implementation of the split/mixed or basal/bolusregimens. One such system is disclosed in U.S. Pat. No. 5,019,974 issuedto Beckers on May 28, 1991. Beckers describes a master computer fordeveloping a therapy program for a patient and for downloading thetherapy program to a patient-operated recorder. The recorder reminds thepatient of any therapy due and records that the therapy has beenperformed by the patient. Data from the recorder is subsequently fedback to the master computer to improve or alter the therapy program.

In using Backers′ system, a patient must strictly adhere to thepredetermined therapy guidelines in order for the therapy program to beeffective. To make any therapy adjustments, the patient must upload datato the master computer, wait for the therapy adjustments, and strictlyfollow the adjusted guidelines. Thus, Beckers′ system restricts thepatient to a consistent meal plan, with no flexibility for adjusting thetherapy program to meals of varying size or timing.

Following a consistent meal plan is extremely difficult, whether fordiabetes treatment or weight loss. Rarely can a patient stick to apredetermined meal plan every day of his or her life. Consequently,Beckers′ system is ineffective for assisting the patient in controllingblood glucose and avoiding hypoglycemia or hyperglycemia when thepatient deviates from the plan during his or her normal course ofbehavior.

Moreover, Beckers′ system lacks any mechanism for predicting thepatient's future blood glucose concentration and is thus unable to alertthe patient to future hypoglycemia or hyperglycemia resulting from anunusual meal or an incorrectly estimated insulin dose taken for themeal. Further, Beckers does not teach or describe any mechanism forrecommending to the patient a corrective action, such as a supplementalinsulin dose or carbohydrate supplement, when the patient has apotential for future hypoglycemia or hyperglycemia.

Another diabetes management system is disclosed in U.S. Pat. No.4,731,726 issued to Allen on Mar. 15, 1988. Allen describes a systemwhich includes a physician computer for downloading therapy guidelinesto a patient-operated apparatus. The apparatus includes a blood glucosemeter for recording a patient's blood glucose values and keys forentering patient data relating to diet, insulin, exercise, stress, andsymptoms of illness. The apparatus is programmed to recommend insulindoses to the patient based upon the data supplied.

Unfortunately, Allen's system recommends insulin doses to the patientbased upon pre-meal blood glucose values only, as stated in column 16,lines 42-44. This forces the patient to wait until the next meal beforehe or she may take action to correct hypoglycemia or hyperglycemiadeveloped since the previous meal. Further, Allen's system has nomechanism for predicting the patient's future blood glucoseconcentration based upon the patient's post-meal blood glucose value andthe insulin action remaining from insulin doses injected before themeal. As a result, Allen's system is unable to alert the patient tofuture hypoglycemia or hyperglycemia resulting from the patient eatingan unusual meal or taking an incorrect insulin dose for the meal.

OBJECTS AND ADVANTAGES OF THE INVENTION

In view of the above, it is an object of the present invention toprovide a diabetes management system for predicting a future bloodglucose concentration of a patient based upon the patient's currentblood glucose concentration and the insulin action remaining fromprevious insulin doses, thereby enabling the patient to take timelycorrective action to prevent hypoglycemia or hyperglycemia. It isanother object of the invention to provide a diabetes management systemfor recommending the corrective action to the patient when the predictedblood glucose value lies outside of a target range.

These and other objects and advantages will become more apparent afterconsideration of the ensuing description and the accompanying drawings.

SUMMARY

The invention presents a system and method for assisting a patienthaving diabetes mellitus in controlling blood glucose. The systemincludes a patient-operated apparatus having a blood glucose meter formeasuring a blood sample of the patient and for producing from ameasurement of the blood sample a blood glucose value G(t_(d))representative of a blood glucose concentration of the patient at timet_(d). The apparatus also includes a user interface for entering in theapparatus an insulin dose value I_(k) representative of an insulin doseadministered to the patient prior to time t_(d.)

The apparatus further includes a memory for storing maximum and minimumvalues defining a target blood glucose range of the patient. The memoryalso stores a target blood glucose value of the patient within therange, an insulin sensitivity value representative of an insulinsensitivity of the patient, and information for determining an insulinaction value F_(k)(t_(d)) representative of a fraction of insulin actionremaining at time t_(d) from the insulin dose.

A processor is connected to the glucose meter, user interface, andmemory. The processor is programmed to determine the insulin actionvalue F_(k)(t_(d)) and to determine a future blood glucose valueG(t_(j)) representative of an expected blood glucose concentration ofthe patient at time t_(j). The processor determines the future bloodglucose value G(t_(j)) in dependence upon the blood glucose valueG(t_(d)), the insulin dose value I_(k), the insulin sensitivity value,and the insulin action value F_(k)(t_(d)). The processor is alsoprogrammed to determine a corrective action for the patient when thefuture blood glucose value G(t_(j)) lies outside of the target range.

The corrective action is preferably an administration of a supplementalinsulin dose when the future blood glucose value G(t_(j)) lies above thetarget range or a consumption of a number of grams of carbohydrates whenthe future blood glucose value G(t_(j)) lies below the target range. Theprocessor is programmed to determine the supplemental insulin dose independence upon the insulin sensitivity value and a difference betweenthe future blood glucose value G(t_(j)) and the target blood glucosevalue. The processor is further programmed to determine the number ofgrams of carbohydrates to be consumed in dependence upon the differencebetween the future blood glucose value G(t_(j)) and the target bloodglucose value. A display is connected to the processor for displayingthe future blood glucose value G(t_(j)) and for recommending thecorrective action to the patient.

The system also includes a healthcare provider computer in communicationwith the apparatus for receiving from the apparatus blood glucose valuesand insulin dose values and for calculating from the values an adjustedinsulin sensitivity value for the patient. The apparatus includes acommunication device, such as a modem and input/output port, connectedto the processor for establishing a communication link between theapparatus and the healthcare provider computer, for transmitting theblood glucose values and insulin dose values through the communicationlink, and for receiving through the communication link the adjustedinsulin sensitivity value.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of a patient-operated apparatus according tothe invention.

FIG. 2 is a schematic block diagram of the apparatus of FIG. 1 connectedto a healthcare provider computer through a communication network.

FIG. 3 is a schematic diagram of the apparatus of FIG. 1 connected tothe healthcare provider computer of FIG. 2 through a connection cord.

FIG. 4 is a sample parameter value entry window as it appears on adisplay of the apparatus of FIG. 1.

FIG. 5 is a graph illustrating the percent of insulin action remainingfrom regular and fast acting insulins as a function of time afterinjection.

FIG. 6A is a sample table showing fractions of insulin action remainingfrom a dose of regular insulin at corresponding time points afterinjection.

FIG. 6B is a continuation of the table of FIG. 6A.

FIG. 7 is a sample table showing fractions of insulin action remainingfrom a dose of fast acting insulin at corresponding time points afterinjection.

FIG. 8A is a flow chart illustrating steps included in a computerprogram executed by the apparatus of FIG. 1.

FIG. 8B is a continuation of the flow chart of FIG. 8A.

FIG. 9A is a flow chart illustrating steps included in a predictionprogram module of the computer program of FIGS. 8A and 8B.

FIG. 9B is a continuation of the flow chart of FIG. 9A.

FIG. 10 is a flow chart illustrating steps included in a graph programmodule of the computer program of FIGS. 8A and 8B.

DETAILED DESCRIPTION

The present invention is a diabetes management system and method forpredicting a future blood glucose value of a patient and forrecommending to the patient a corrective action when the future bloodglucose value lies outside of a target blood glucose range. In thefollowing description, numerous specific details are set forth in orderto provide a thorough understanding of the present invention. However,it will be apparent to one of ordinary skill in the art that thesespecific details need not be used to practice the invention. In otherinstances, well known structures, interfaces, and processes are notshown in detail to avoid unnecessarily obscuring the present invention.

FIGS. 1-7 illustrate a diabetes management system according to apreferred embodiment of the invention. Referring to FIG. 1, the diabetesmanagement system includes a patient-operated apparatus 10 having ahousing 12 for holding the components of apparatus 10. Housing 12 ispreferably sufficiently compact to enable apparatus 10 to be hand-heldand carried by a patient. A strip guide 18 for receiving a blood glucosetest strip 20 is located on a surface of housing 12. Test strip 20 isfor receiving a blood sample from the patient.

Apparatus 10 includes a display 14 for displaying predicted future bloodglucose values and for recommending to the patient corrective actionswhen the future blood glucose values lie outside of a target bloodglucose range. Display 14 is preferably a liquid crystal display (LCD).Display 14 is also designed to display prompts and a menu 46 to thepatient during the operation of apparatus 10.

Menu 46 preferably includes a number of menu options as follows. The“DOSE” option starts a procedure for entering in apparatus 10 insulindose values representative of insulin doses administered to the patient.Each insulin dose is typically self-injected by the patient. Afterinjecting a dose, the patient selects the “DOSE” option to record inapparatus 10 the dose value and the type of insulin injected. The “TESTBG” option starts a procedure for measuring a current blood glucosevalue of the patient. The “PREDICT” option starts a procedure forpredicting a future blood glucose value of the patient.

The “VALUES” option starts a procedure for entering in apparatus 10various parameter values used to predict the future blood glucose valuesand to recommend appropriate corrective actions to the patient. The“SEND” option starts a procedure for transmitting the blood glucosevalues and insulin dose values stored in apparatus 10 to a healthcareprovider computer. The “RECEIVE” option starts a procedure for receivingdata from the healthcare provider computer.

Display 14 is also designed to display the predicted future bloodglucose values in graphical form. Display 14 preferably displays a graph48 which includes a blood glucose value curve 50 generated from thepredicted blood glucose values. Graph 48 also includes a hypoglycemicline 52 indicating a hypoglycemic threshold of the patient and ahyperglycemic line 53 indicating a hyperglycemic threshold of thepatient. Apparatus 10 also includes an audio transducer, such as aspeaker 54, for audibly alerting the patient when a predicted futureblood glucose value lies below the hypoglycemic threshold.

Apparatus 10 further includes a keypad 16 having a number of keys asfollows. The ON/OFF key is pressed to turn apparatus 10 on and off.Number keys 0, 1, 2, 3, etc. are used for entering information ondisplay 14, such as insulin dose values, insulin types, and dates andtimes of injections. The ENTER key is used after operation of the numberkeys to enter the information in apparatus 10. The ENTER key is alsoused to select menu options. The CLEAR key is used to clear numberswhich have been entered incorrectly. The YES and NO keys are pressed inresponse to prompts on display 14 which require a yes or no answer.

The MENU key is pressed to display menu 46 on display 14. The ARROW keysare for scrolling through the menu options. Specific techniques formanufacturing and using an electronic apparatus having these keys arewell known in the art. Further, those skilled in the art will recognizethat the keys may be replaced by other user controls, such as switches,buttons, or graphic controls implemented on a touch sensitive screen.

FIG. 2 is a schematic block diagram illustrating apparatus 10 in greaterdetail. Apparatus 10 includes a microprocessor 22 and a memory 24connected to microprocessor 22. Microprocessor 22 is designed to executea computer program stored in memory 24 to perform the variouscalculations and control functions which are described in the operationsection below.

Keypad 16 is connected to microprocessor 22 through a standard keypaddecoder 26 . Display 14 is connected to microprocessor 22 through adisplay driver 30. Microprocessor 22 communicates with display driver 30via an interface, and display driver 30 updates and refreshes display 14under the control of microprocessor 22. Speaker 54 and a clock 56 arealso connected to microprocessor 22. Speaker 54 operates under thecontrol of microprocessor 22 to emit audible tones alerting the patientto possible future hypoglycemia. Clock 56 supplies the current date andtime to microprocessor 22.

Memory 24 also stores blood glucose values of the patient, the insulindose values, the insulin types, and the parameter values used bymicroprocessor 22 to calculate future blood glucose values, supplementalinsulin doses, and carbohydrate supplements. Each blood glucose valueand insulin dose value is stored in memory 24 with a corresponding dateand time. Memory 24 is preferably a non-volatile memory, such as anelectrically erasable read only memory (EEPROM).

Apparatus 10 also includes a blood glucose meter 28 connected tomicroprocessor 22. Glucose meter 28 is designed to measure blood samplesreceived on blood glucose test strips and to produce blood glucosevalues from measurements of the blood samples. Such glucose meters arewell known in the art. Glucose meter 28 is preferably of the type whichproduces digital values which are output directly to microprocessor 22.Alternatively, blood glucose meter 28 may be of the type which producesanalog values. In this alternative embodiment, blood glucose meter 28 isconnected to microprocessor 22 through an analog to digital converter(not shown).

Apparatus 10 further includes an input/output port 34, preferably aserial port, which is connected to microprocessor 22. Port 34 isconnected to a modem 32 by an interface, preferably a standard RS232interface. Modem 32 is for establishing a communication link betweenapparatus 10 and a healthcare provider computer 38 through acommunication network 36. Modem 32 is capable of transmitting data toand receiving data from provider computer 38 through communicationnetwork 36. In the preferred embodiment, communication network 36 is atelephone network and modem 32 establishes the communication link tocomputer 38 through telephone lines.

Referring to FIG. 3, the input/output port may also be used to establishan alternative communication link between apparatus 10 and computer 38through a data connection cord 40. Connection cord 40 is connectable tothe input/output port of apparatus 10 and to a correspondinginput/output port of healthcare provider computer 38. Specifictechniques for connecting electronic devices through connection cordsare well known in the art.

Healthcare provider computer 38 is preferably a personal computerlocated at a healthcare provider site, such as the office of thepatient's physician. Healthcare provider computer 38 is designed toreceive the patient's blood glucose values and insulin dose values fromapparatus 10 and calculate from the values an adjusted insulinsensitivity value for the patient, as will be explained in the operationsection below.

The computer program executed by microprocessor 22 includes equationsfor calculating future blood glucose values, supplemental insulin doses,and carbohydrate supplements. The variables used in the computer programare defined as follows:

t₁, t₂, ...t_(d), ...t_(j).... t_(M)=time points.

G(t_(d))=blood glucose value representative of a blood glucoseconcentration of the patient at time t_(d).

G(t_(j))=future blood glucose value representative of an expected bloodglucose concentration of the patient at time t_(j).

I_(k)=insulin dose value representative of an insulin dose kadministered to the patient prior to time t_(d), where k=1 to N andN=the total number of bolus and supplemental insulin doses administeredto the patient. Insulin dose value I_(k) is preferably expressed inunits of insulin.

P_(k)=insulin type of insulin dose k, e.g. regular insulin or fastacting lispro insulin.

F_(k)(t_(d))=insulin action value representative of the fraction ofinsulin action remaining at time t_(d) from insulin dose k. For thepurposes of this specification and the appended claims, insulin actionis defined as the action of insulin to lower a patient's blood glucoseconcentration.

F_(k)(t_(j))=insulin action value representative of a fraction ofinsulin action remaining at time t_(j) from insulin dose k.

S=insulin sensitivity value representative of an insulin sensitivity ofthe patient. Insulin sensitivity value S indicates the amount a unit ofinsulin is expected to lower the patient's blood glucose concentration.Value S is a variable which is preferably updated in response to datacollection from the patient, as described in detail below.

D=a recommended supplemental dose of insulin calculated for the patient.Dose D is preferably expresses in units of insulin.

C=carbohydrate value indicating the amount one gram of carbohydrates isexpected to raise the patient's blood glucose concentration.

R_(max), R_(min)=maximum and minimum values, respectively, defining atarget blood glucose range of the patient.

T=target blood glucose value of the patient within the target bloodglucose range.

H=Hypoglycemic value indicating a hypoglycemic threshold of the patientbelow which a carbohydrate supplement is desired.

B=the number of grams of carbohydrates to be consumed by the patient ina recommended carbohydrate supplement.

With these definitions, future blood glucose value G(t_(j)) iscalculated according to equation (1): $\begin{matrix}{{G\left( t_{\quad j} \right)} = {{G\left( t_{d} \right)} - {S\left\lbrack {\sum\limits_{k = 1}^{N}{I_{k}\left( {{F_{k}\left( t_{d} \right)} - {F_{k}\left( t_{j} \right)}} \right)}} \right\rbrack}}} & (1)\end{matrix}$

Microprocessor 22 calculates future blood glucose value G(t_(j)) fromblood glucose value G(t_(d)), insulin sensitivity value S, insulin dosevalue I_(k), and insulin action values F_(k)(t_(d)) and F_(k)(t_(j)). Ifthe patient has injected multiple insulin doses, their remaining actionis summed as shown. Blood glucose value G(t_(d)) is preferably measureda sufficient time after the patient's last meal to ensure that most orall of the meal has already been absorbed. A sufficient time is usuallytwo hours after a typical meal, or one hour after a snack or smallermeal.

FIG. 4 shows a sample parameter value entry window 58 as it appears ondisplay 14. Window 58 is preferably a pop-up window displayed when thepatient selects the “VALUES” option from the menu. Window 58 includesdata entry fields 60 for entering in apparatus 10 insulin sensitivityvalue S, carbohydrate value C, hypoglycemic value H, maximum valueR_(max), minimum value R_(min), and target value T. The patientnavigates between entry fields 60 using the arrow keys on the keypad.

Apparatus 10 uses information derived from insulin time activityprofiles to determine the insulin action values. The time activityprofiles of insulin are described in several sources, such as Eli Lillyand Company's websitehttp://www.lilly.com/diabetes/ref₁₃manual/insulin₁₃bck.html. The timeactivity profiles of insulin are also described in Howey et al. “ARapidly Absorbed Analogue of Human Insulin”, Diabetes, Vol. 43, pp.396-402, 1994, which is hereby incorporated by reference.

FIG. 5 is a graph illustrating the percent of insulin action remainingfrom doses of regular and lispro insulins as a function of time afterinjection. The graph includes two insulin action curves derived fromdata in Howey et al. A first insulin action curve 42 shows the percentof insulin action remaining from a dose of regular insulin as a functionof time after injection. A second insulin action curve 44 shows thepercent of insulin action remaining from a dose of lispro insulin as afunction of time after injection.

An insulin action value is determined from curves 42 or 44 bydetermining the time after injection, locating the correspondingpercentage of insulin action remaining on the appropriate curve, anddividing the percentage by 100 to yield the insulin action value. Forexample, if the patient injected a dose of lispro and the time afterinjection equals 150 minutes, then the insulin action value isdetermined to be 0.40 from curve 44. This indicates that at 150 minutesafter injection, the insulin dose has 40% of its full insulin actionremaining to lower the patient's blood glucose concentration.

The insulin action curves shown in FIG. 5 are derived from standardpatient data. An insulin action curve customized to an individualpatient may be generated experimentally by establishing basalhomeostasis in the patient and then measuring the effect of asupplemental insulin dose on the patient's blood glucose concentration.After injecting the supplemental insulin dose, the patient's bloodglucose is measured frequently over the period of time required for theinsulin to be fully absorbed.

The measured blood glucose values are used to generate a curve of thepatient's blood glucose concentration as a function of time afterinjection. The total blood glucose drop resulting from the supplementalinsulin dose is determined by subtracting the last blood glucose valuefrom the first blood glucose value. The curve is normalized bysubtracting the final blood glucose value from each point on the curveand dividing the result by the total blood glucose drop. Normalizing thecurve in this manner yields an insulin action curve individualized tothe patient. This experiment is repeated, preferably at varying times ofday, to generate a continuous insulin action curve for the patient.

In the preferred embodiment, information for determining insulin actionvalues F_(k)(t_(d)) and F_(k)(t_(j)) is stored in memory 24 in tabularform. The information may be derived from standard insulin action curvesor derived from an insulin action curve individualized to the patient.FIGS. 6A and 6B show a first insulin action Table 1 which is derivedfrom curve 42, the insulin action curve for regular insulin.

FIG. 7 shows a second insulin action Table 2 which is derived from curve44, the insulin action curve for lispro insulin. Each insulin actiontable includes a first column containing time points after injection anda second column containing corresponding insulin action values.Microprocessor 22 preferably uses linear interpolation to determineinsulin action values F_(k)(t_(d)) and F_(k)(t_(j)) from the insulinaction tables, as will be described in the operation section below.

The operation of the preferred embodiment is illustrated in FIGS. 1-10.Referring to FIG. 2, a preferred method of using the diabetes managementsystem to assist a patient having diabetes mellitus in controlling bloodglucose includes the step of storing in memory 24 insulin sensitivityvalue S, carbohydrate value C, hypoglycemic value H, maximum valueR_(max), minimum value R_(min), target blood glucose value T, and thetable values for determining remaining insulin action at correspondingtimes after injection. The values may be entered in apparatus 10 throughinput/output port 34 or keypad 16. The values stored in memory 24 arepreferably selected under the supervision of a healthcare provider, suchas the patient's physician.

Insulin sensitivity value S is preferably customized to the patientbased upon the patient's measured blood glucose values and insulin dosevalues, as will be explained in detail below. However, when the patientis first provided with apparatus 10, historical blood glucose values andinsulin dose values may not be available. In this case, insulinsensitivity value S is preferably estimated by dividing 1,500 mg/dl bythe patient's total daily insulin need. For example, if the patient'stotal daily insulin need is 30 units, the initial insulin sensitivityvalue is calculated as 50 mg/dl per unit of insulin.

Specific techniques for establishing carbohydrate value C, hypoglycemicvalue H, maximum value R_(max), minimum value R_(min), and target bloodglucose value T are well known in the art. For example, many physiciansprefer a target blood glucose range of 100-150 mg/dl with a target bloodglucose value of 120 mg/dl and a hypoglycemic value of 70 mg/dl.Carbohydrate value C is preferably selected in dependence upon thepatient's weight. For example, one gram of carbohydrates typicallyraises blood glucose concentrations by 3 mg/dl, 4 mg/dl, and 5 mg/dl forpeople who weigh 90 kg, 70 kg, and 45 kg, respectively.

Apparatus 10 is used by the patient to predict a future blood glucosevalue and to generate a corrective action when the predicted value liesoutside of the patient's target blood glucose range. FIG. 8A is a flowchart illustrating steps included in the computer program executed bymicroprocessor 22 to perform these functions. FIG. 8B is a continuationof the flow chart of FIG. 8A.

In step 102, microprocessor 22 determines if the patient has selectedthe “DOSE” option from menu 46. If the patient has not selected the“DOSE” option, microprocessor 22 proceeds to step 106. If the patienthas selected the “DOSE” option, microprocessor 22 proceeds to step 104,entering and storing dose value I_(k) and insulin type P_(k).

To enter and store dose value I_(k) and insulin type P_(k),microprocessor 22 displays the prompt “ENTER DOSE IN UNITS OF INSULIN”on display 14. The patient then enters dose value I_(k) intomicroprocessor 22 through keypad 16. The patient is then prompted with“ENTER INSULIN TYPE: PRESS 1 FOR REGULAR OR 2 FOR LISPRO”. The patiententers insulin type P_(k) into microprocessor 22 by pressing the keycorresponding to the insulin type injected.

Microprocessor 22 then prompts the patient with “ENTER DATE/TIME OFINJECTION OR PRESS 1 FOR CURRENT DATE/TIME”. The patient enters the dateand time of injection or selects the current date and time if the doseentry is made immediately after the injection. Microprocessor 22 storesdose value I_(k) and insulin type P_(k) in memory 24 with the selecteddate and time. Following step 104, microprocessor 22 proceeds to step106.

In step 106, microprocessor 22 determines if the patient has selectedthe “TEST BG” option from menu 46. If the patient has not selected the“TEST BG” option, microprocessor 22 proceeds to step 118. If the patienthas selected the “TEST BG” option, microprocessor 22 prompts the patientto place a blood sample on a blood glucose test strip and to insert thetest strip in strip guide 18, step 108.

Glucose meter 28 measures the blood sample and produces blood glucosevalue G(t_(d)) from the measurement of the blood sample. In step 110,blood glucose value G(t_(d)) is entered in microprocessor 22 by glucosemeter 28, coded and labeled with the date and time of the measurement,and stored in memory 24. Blood glucose value G(t_(d)) is also displayedto the patient on display 14 in step 112.

In step 114, microprocessor 22 determines if the patient has selectedthe “PREDICTION” option from menu 46. If the patient has not selectedthe “PREDICTION” option, microprocessor 22 proceeds to step 118. If thepatient has selected the “PREDICTION” option, microprocessor 22 executesa future blood glucose value program module in step 116. The stepsincluded in the future blood glucose value program module areillustrated in the flow chart of FIGS. 9A and 9B and will be describedin detail below. After executing the program module of step 116,microprocessor 22 proceeds to step 118.

In step 118, microprocessor 22 determines if the patient has selectedthe “VALUES” option from menu 46. If the patient has not selected the“VALUES” option, microprocessor 22 proceeds to step 124. If the patienthas selected the “VALUES” option, microprocessor 22 displays on display14 the parameter value entry window 58, step 120. In step 122, theparameter values are entered in microprocessor 22 through keypad 16 andstored in memory 24. Following step 122, microprocessor 22 proceeds tostep 124.

In step 124, microprocessor 22 determines if the patient has selectedthe “SEND” option from menu 46. If the patient has not selected the“SEND” option, microprocessor 22 proceeds to step 128. If the patienthas selected the “SEND” option, microprocessor 22 prompts the patient toconnect modem 32 to a telephone line. Microprocessor 22 then transmitsthe blood glucose values and insulin dose values stored in memory 24 tohealthcare provider computer 38 through network 36, step 126.Microprocessor 22 then proceeds to step 128.

In step 128, microprocessor 22 determines if the patient has selectedthe “RECEIVE” option from menu 46. If the patient has not selected the“RECEIVE” option, microprocessor 22 returns to step 102 and repeats theprogram steps until apparatus 10 is turned off by the patient. If thepatient has selected the “RECEIVE” option, microprocessor 22 prompts thepatient to connect modem 32 to a telephone line. In step 130,microprocessor 22 receives data from healthcare provider computer 38through network 36.

The data preferably includes an adjusted insulin sensitivity value andmay optionally include new maximum and minimum values defining thepatient's target blood glucose range, a new target blood glucose value,and new insulin action table values for determining remaining insulinaction. In step 132, microprocessor 22 stores the received data inmemory 24 for use in subsequent calculations. Following step 132,microprocessor 22 returns to step 102 and repeats the program stepsuntil apparatus 10 is turned off by the patient.

FIGS. 9A and 9B illustrate the steps included in the future bloodglucose value program module of step 116. In step 202, microprocessor 22determines if the patient wishes to see future blood glucose valueG(t_(j)) predicted for a default ultimate time point by displaying theprompt “USE ULTIMATE TIME IN PREDICTION? YES/NO?”. In the preferredembodiment, the ultimate time point is the time point at which the lastinsulin dose k injected by the patient will be fully absorbed and haveno insulin action remaining. In response to a NO input from the patient,microprocessor 22 proceeds to step 208. In response to a YES input fromthe patient, microprocessor 22 sets time t_(j) equal to the ultimatetime point, step 204.

To set time t_(j) equal to the ultimate time point, microprocessor 22retrieves from memory 24 the last insulin dose value I_(k) andcorresponding insulin type P_(k) entered by the patient. If the insulintype P_(k) is regular insulin, microprocessor 22 retrieves from Table 1the time after injection value corresponding to 0.00 insulin actionremaining, i.e. 720 minutes. If the insulin type P_(k) is lisproinsulin, microprocessor 22 retrieves from Table 2 the time afterinjection value corresponding to 0.00 insulin action remaining, i.e. 390minutes.

Microprocessor 22 adds the retrieved time after injection value to thetime of injection stored with the last dose value I_(k) and sets timet_(j) equal to the sum. When time t_(j) is selected to be the ultimatetime point, each insulin dose k injected by the patient will have noremaining insulin action at time t_(j). Accordingly, microprocessor 22sets insulin action value F_(k)(t_(j)) equal to 0 for each dose valueI_(k) stored in memory 24, step 206. Following step 206, microprocessor22 proceeds to step 212.

If the patient has not selected the ultimate time point for time t_(j),microprocessor 22 prompts the patient to specify time t_(j) bydisplaying “ENTER TIME FOR PREDICTION”. The patient then enters timet_(j) in microprocessor 22 in step 208. In step 210, microprocessor 22determines insulin action values F_(k)(t_(j)) for each dose value I_(k)stored in memory 24. Microprocessor 22 preferably determines insulinaction values F_(k)(t_(j)) using linear interpolation.

The insulin action value F_(k)(t_(j)) for each dose value I_(k) is alsodetermined in dependence upon its corresponding insulin type P_(k). Ifthe insulin type is regular insulin, microprocessor 22 determines theinsulin action value F_(k)(t_(j)) by interpolating between the valueslisted in Table 1. If the insulin type is lispro insulin, microprocessor22 determines the insulin action value F_(k)(t_(j)) by interpolatingbetween the values listed in Table 2.

The interpolation is preferably performed as follows. For each dosevalue I_(k), microprocessor 22 calculates a time after injection valueX_(k) indicating the time differential between time t_(j) and the timeof injection of dose k. Microprocessor 22 then retrieves four valuesfrom the appropriate insulin action table. The four values retrieved area first time after injection value X₀ and its corresponding insulinaction value Y₀, and a second time after injection value X₁ and itscorresponding insulin action value Y₁.

Value X₀ is selected from the appropriate table as the time afterinjection value which is closest to value X_(k) without exceeding valueX_(k). Value X₁ is selected as the time after injection value in thenext row of the table. Microprocessor 22 preferably calculates theinsulin action value F_(k)(t_(j)) for each dose value according toequation (2A): $\begin{matrix}{{F_{k}\left( t_{j} \right)} = {Y_{0} + {\frac{\left( {X_{k} - X_{0}} \right)\left( {Y_{1} - Y_{0}} \right)}{\left( {X_{1} - X_{0}} \right)}.}}} & \text{(2A)}\end{matrix}$

For example, if the patient enters a dose value indicating a dose ofregular insulin was injected at 12:00 PM and specifies a time t_(j) of2:20 PM, microprocessor 22 first calculates time after injection valueX_(k) to be 140 minutes. Microprocessor 22 then retrieves from Table 1the values X₀=135 minutes, Y₀=0.70, X₁=150 minutes, and Y₁=0.64.Microprocessor 22 calculates insulin action value F_(k)(t_(j)) for thedose from equation (2A) as:${F_{k}\left( t_{j} \right)} = {{0.70 + \frac{\left( {140 - 135} \right)\left( {0.64 - 0.70} \right)}{\left( {150 - 135} \right)}} = 0.68}$

Microprocessor 22 thus determines that the regular insulin dose injectedat 12:00 PM will have 68% of its insulin action remaining at 2:20 PM.Specific techniques for performing linear interpolations in this mannerare well known in the art. Further, those skilled in the art willrecognize that the insulin action tables could be provided with shortertime intervals between the time points to provide as much precision andaccuracy as desired in the interpolation.

In step 212, microprocessor 22 performs a similar linear interpolationto determine the insulin action values F_(k)(t_(d)) for each dose valueI_(k) stored in memory 24. The insulin action value F_(k)(t_(d)) foreach dose value I_(k) is also determined in dependence upon itscorresponding insulin type P_(k). If the insulin type is regularinsulin, microprocessor 22 determines the value F_(k)(t_(d)) byinterpolating between the values listed in Table 1. If the insulin typeis lispro insulin, microprocessor 22 determines the value F_(k)(t_(d))by interpolating between the values listed in Table 2.

For each dose value I_(k), microprocessor 22 calculates a time afterinjection value Z_(k) indicating the time differential between timet_(d) and the time of injection of dose k. Microprocessor 22 thenretrieves from the appropriate insulin action table the first time afterinjection value X₀, the corresponding insulin action value Y₀, thesecond time after injection value X₁, and the corresponding insulinaction value Y₁. Value X₀ is selected from the appropriate table as thetime after injection value which is closest to value Z_(k) withoutexceeding value Z_(k). Value X₁ is selected as the time after injectionvalue in the next row of the table. Microprocessor 22 calculates eachinsulin action value F_(k)(t_(d)) according to equation (2B):$\begin{matrix}{{F_{k}\left( t_{d} \right)} = {Y_{0} + {\frac{\left( {Z_{k} - X_{0}} \right)\left( {Y_{1} - Y_{0}} \right)}{\left( {X_{1} - X_{0}} \right)}.}}} & \text{(2B)}\end{matrix}$

For example, if the patient enters a dose value indicating a dose oflispro insulin was injected at 8:30 PM and time t_(d) is 11:00 PM,microprocessor 22 first calculates time after injection value Z_(k) tobe 150 minutes. Microprocessor 22 then retrieves from Table 2 the valuesX₀=150 minutes, Y₀=0.40, X₁=165 minutes, and Y₁=0.32. Microprocessor 22calculates insulin action value F_(k)(t_(d)) for the dose from equation(2B) as:${F_{k}\left( t_{d} \right)} = {{0.40 + \frac{\left( {150 - 150} \right)\left( {0.32 - 0.40} \right)}{\left( {165 - 150} \right)}} = 0.40}$

Microprocessor 22 thus determines that the lispro insulin dose injectedat 8:30 PM has 40% of its insulin action remaining at 11:00 PM. In step214, microprocessor 22 calculates predicted future blood glucose valueG(t_(j)) according to equation (1): $\begin{matrix}{{G\left( t_{\quad j} \right)} = {{G\left( t_{d} \right)} - {S\left\lbrack {\sum\limits_{k = 1}^{N}{I_{k}\left( {{F_{k}\left( t_{d} \right)} - {F_{k}\left( t_{j} \right)}} \right)}} \right\rbrack}}} & (1)\end{matrix}$

Future blood glucose value G(t_(j)) is then displayed to the patient ondisplay 14, step 216. In step 218, microprocessor 22 determines if thepatient wishes to see graph 48 by displaying the prompt “DISPLAY GRAPH?YES/NO?”. In response to a NO input from the patient, microprocessor 22proceeds to step 222. In response to a YES input from the patient,microprocessor 22 executes a graph program module in step 220. The stepsincluded in the graph program module are illustrated in the flow chartof FIG. 10 and will be described in detail below. After executing theprogram module of step 220, microprocessor 22 proceeds to step 222.

In step 222, microprocessor 22 compares future blood glucose valueG(t_(j)) to maximum value R_(max) and minimum value R_(min) to determineif future blood glucose value G(t_(j)) lies outside of the patient'starget blood glucose range. If glucose value G(t_(j)) does not lieoutside of the target range, “NO CORRECTIVE ACTION REQUIRED” isdisplayed to the patient in step 224. Following step 224, the futureblood glucose value program module ends.

If glucose value G(t_(j)) lies outside of the target range,microprocessor 22 determines a corrective action for the patient andrecommends the corrective action to the patient on display 14. In step226, microprocessor 22 determines if glucose value G(t_(j)) is greaterthan maximum value R_(max). If glucose value G(t_(j)) is not greaterthan maximum value R_(max), microprocessor 22 proceeds to step 234.

If glucose value G(t_(j)) is greater than maximum value R_(max),microprocessor 22 calculates a supplemental insulin dose D for thepatient and displays insulin dose D on display 14, step 228.Microprocessor 22 preferably calculates supplemental insulin dose D independence upon insulin sensitivity value S and a difference betweenfuture blood glucose value G(t_(j)) and target blood glucose value Taccording to equation (3):

D=(G(t _(j))−T)/S  (3).

After displaying supplemental insulin dose D, microprocessor 22determines if the patient wishes to enter a dose value for thesupplemental insulin dose by displaying the prompt “SUPPLEMENTAL INSULINTAKEN? YES/NO?”, step 230. In response to a NO input from the patient,the program module ends. In response to a YES input, microprocessor 22proceeds to step 232, entering and storing the dose value and insulintype of supplemental insulin dose D. Step 232 is analogous to step 104previously described with reference to FIG. 7A. Following step 232, theprogram module ends.

In step 234, microprocessor 22 determines if glucose value G(t_(j)) isless than hypoglycemic value H. If future blood glucose value G(t_(j))is not less than hypoglycemic value H, microprocessor 22 proceeds tostep 240. If glucose value G(t_(j)) lies below hypoglycemic value H,microprocessor 22 audibly alerts the patient by causing speaker 54 toemit audible tones, step 236. This alerts the patient that he or she islikely to develop hypoglycemia unless a carbohydrate supplement istaken.

In step 238, microprocessor 22 calculates a number B of grams ofcarbohydrates to be consumed by the patient and displays arecommendation to consume number of grams B, step 238. Following step238, the program module ends. Microprocessor 22 preferably calculatesnumber of grams B in dependence upon carbohydrate value C and thedifference between future blood glucose value G(t_(j)) and target bloodglucose value T according to equation (4):

B=(T−G(t _(j)))/C  (4).

If future blood glucose value G(t_(j)) is not less than hypoglycemicvalue H, then glucose value G(t_(j)) lies in a range betweenhypoglycemic value H and minimum value R_(min).

In this case, microprocessor 22 displays to the patient “POSSIBLE FUTUREHYPOGLYCEMIA: RECOMMEND SUBSEQUENT GLUCOSE MEASUREMENT IN 1.5 HOURS”,step 240. Following step 240, the program module ends. Because thepatient's blood glucose concentration may rebound, it is presentlypreferred not to recommend a carbohydrate supplement unless future bloodglucose value G(t_(j)) is below hypoglycemic value H.

FIG. 10 is a flow chart illustrating the steps included in the graphprogram module of step 220. In steps 302-310, microprocessor 22generates a plurality of predicted future blood glucose values forvarious time points between time t_(d) and time t_(j). The future bloodglucose values are used to generate blood glucose value curve 50 ofgraph 48. In the preferred embodiment, the future blood glucose valuesare calculated for time points which increase from time t_(d) to timet_(j).in five minute increments. It is obvious that the time incrementsmay be varied as desired in alternative embodiments.

In step 302, microprocessor 22 sets time t_(j) equal to time t_(d) plusfive minutes. In step 304, microprocessor 22 determines insulin actionvalues F_(k)(t_(j)) for each dose value I_(k) stored in memory 24. Step304 is analogous to step 210 previously described with reference to FIG.9A. In step 306, microprocessor 22 calculates future blood glucose valueG(t_(j)). Step 306 is analogous to step 214 previously described withreference to FIG. 9A.

In step 308, microprocessor 22 determines if time t_(j) is greater thanor equal to the ultimate time point at which the last insulin dose kinjected by the patient will have no insulin action remaining. If timet_(j) is not greater than or equal to the ultimate time point,microprocessor 22 sets time t_(j) equal to time t_(j) plus five minutes,step 310. Microprocessor 22 then repeats steps 304-308 to calculate asubsequent future blood glucose value.

If time t_(j) is greater than or equal to the ultimate time point,microprocessor 22 generates blood glucose value curve 50 from thecalculated future blood glucose values and displays graph 48 on display14, step 312. Following step 312, the graph program module ends. Asshown in FIG. 1, graph 48 includes line 52 indicating the patient'shypoglycemic threshold and line 53 indicating the patient'shyperglycemic threshold. Lines 52 and 53 enable the patient to determinethe time point at which he or she is predicted to develop hypoglycemiaand hyperglycemia, respectively.

The diabetes management system of the present invention provides asignificant improvement over conventional diabetes management systems byalerting the patient to the possible development of hypoglycemia orhyperglycemia between meals, thereby allowing the patient to take earlycorrective action. Conventional management systems are unable to accountfor the insulin action remaining from previous insulin doses andtherefore restrict insulin supplements to pre-meal times. Thus, in usingthese conventional systems, the patient must wait until the next mealtime to correct hyperglycemia, and may develop hypoglycemia withoutwarning.

The following is an illustrative example of how apparatus 10 assists apatient in preventing hyperglycemia between meals. The example assumesthe patient has an insulin sensitivity value of 40 mg/dl per unit, atarget blood glucose range of 100 mg/dl-150 mg/dl, a target bloodglucose value of 120 mg/dl, a hypoglycemic value of 70 mg/dl, and acarbohydrate value of 4 mg/dl per gram.

In the example, the patient eats a late dinner at 8:40 PM. Beforeeating, the patient estimates that the meal requires 15 units of bolusinsulin and injects 15 units of lispro at 8:30 PM. The patient recordsthe dose value, dose type, and time of injection in apparatus 10. Atbedtime, 11:00 PM, the patient uses apparatus 10 to measure his or herblood glucose value. Apparatus 10 produces and displays to the patient acurrent blood glucose value of 480 mg/dl. The patient then requestsapparatus 10 to predict a future blood glucose value at the ultimatetime point.

Microprocessor 22 retrieves from memory 24 the dose value andcorresponding insulin type of the dose injected by the patient at 8:30PM. Microprocessor 22 calculates time after injection value Z_(k) to be150 minutes. Microprocessor 22 then retrieves from Table 2 the valuesX₀=150 minutes, Y₀=0.40, X₁=165 minutes, and Y₁=0.32. Microprocessor 22calculates insulin action value F_(k)(t_(d)) from equation (2B) as:${F_{k}\left( t_{d} \right)} = {{0.40 + \frac{\left( {150 - 150} \right)\left( {0.32 - 0.40} \right)}{\left( {165 - 150} \right)}} = {0.40.}}$

Microprocessor 22 thus determines that the lispro insulin dose injectedat 8:30 PM has 40% of its insulin action remaining at 11:00 PM.Microprocessor 22 also sets insulin action value F_(k)(t_(j)) equal to0.0 for each dose value stored in memory 24. For simplicity ofunderstanding, the example assumes that only the dose injected at 8:30PM has remaining insulin action. Microprocessor 22 then calculates thepredicted blood glucose value at 3:00 AM according to equation (1) as:

G(t _(j))=480−40(15×.40)=240 mg/dl.

This indicates that the patient can expect an ultimate blood glucosevalue of 240 mg/dl when the insulin dose has been completely absorbed.The predicted value of 240 mg/dl is greater than the patient's maximumvalue of 150 mg/dl, so microprocessor 22 calculates a supplementalinsulin dose for the patient and displays the recommended supplement ondisplay 14. The supplemental dose D is calculated from equation (3) as:

D=(240−120)/40=3 units of supplemental insulin.

The patient takes the supplemental insulin dose and records the dosevalue in apparatus 10. From taking the supplemental insulin dose, thepatient obtains eight hours of normal blood glucose in place ofhyperglycemia. An adjusted insulin sensitivity may also be determinedfrom the dose values and measured blood glucose values recorded inapparatus 10 as follows. The next morning, the patient measures his orher pre-breakfast blood glucose value using apparatus 10. The patientthen transmits the recorded dose values and blood glucose valuesmeasured at bedtime and before breakfast to healthcare provider computer38.

An adjusted insulin sensitivity value is calculated in healthcareprovider computer 38 by subtracting the pre-breakfast blood glucosevalue from the bedtime blood glucose value. The result is divided by thetotal number of units of insulin which had remaining insulin action atbedtime. The number of units of insulin having remaining insulin actionat bedtime is equal to the total number of units of the supplementalinsulin dose plus the fraction of any previously injected insulin doseshaving remaining action.

An illustrative example will now be given using the same valuespresented above, where the patient's bedtime blood glucose value equals480 mg/dl, the supplemental insulin dose value equals 3 units, and thefraction of insulin action remaining from a previous 15 unit insulindose is 0.40. The present example further assumes a pre-breakfast bloodglucose value of 138 mg/dl measured the following morning. The adjustedsensitivity value is calculated as:

S=(480 −138)/(3+(15×0.40))=38 mg/dl per unit.

The insulin sensitivity value S is preferably updated over time as amoving average of the individually calculated sensitivity values.

A second example illustrates how apparatus 10 assists a patient inpreventing hypoglycemia. The second example assumes the same valuespresented in the first example except that the patient's blood glucosevalue at 11:00 PM is now assumed to be 280 mg/dl. Microprocessor 22calculates the predicted glucose value at 3:00 AM from equation (1) as:

G(t _(j))=280−40(15×0.40)=40 mg/dl.

The predicted value of 40 mg/dl is less than the patient's hypoglycemicvalue of 70 mg/dl. Accordingly, microprocessor 22 calculates acarbohydrate supplement and displays the number of grams ofcarbohydrates to be consumed by the patient. The number of grams ofcarbohydrates is calculated from equation (4) as:

B=(120 mg/dl−40 mg/dl)/4=20 grams.

The patient consumes the carbohydrate supplement and successfully avoidshypoglycemia.

SUMMARY, RAMIFICATIONS, AND SCOPE

Although the above description contains many specificities, these shouldnot be construed as limitations on the scope of the invention but merelyas illustrations of the presently preferred embodiment. Many otherembodiments of the invention are possible. For example, the system ofthe invention may be implemented in many different hardwareconfigurations. It is presently preferred to provide the patient with asmall, portable apparatus to facilitate use of the apparatus throughoutthe day. However, in alternative embodiments, the apparatus may comprisea personal computer, a multi-media processor connected to a television,or any other electronic device capable of performing the functionsdescribed.

Additionally, the system is not limited to establishing a communicationlink between the apparatus and healthcare provider computer through atelephone line or data connection cord. Those skilled in the art willrecognize that the apparatus may be placed in communication with thehealthcare provider computer through a computer network, a wirelesscommunication network, or a data storage card, such as a smart card,exchanged between the physician and patient. Specific techniques forestablishing communication links between a physician and a remotelylocated patient are well known in the art.

The insulin sensitivity values and insulin action values for determiningremaining insulin action may differ in alternative embodiments. Thevalues shown in the preferred embodiment are exemplary of one possibleembodiment of the invention and are not intended to limit its scope.Further, the insulin action values may be derived from standard data orderived from the blood glucose values and insulin dose values of anindividual patient. The insulin action values may be further customizedto the individual patient in dependence upon the patient's preferredmode of insulin administration, e.g. syringe injections into the thigh,gut, or arm, insulin pump administrations, or inhalation.

Further, the insulin action values need not be stored in tabular form.In an alternative embodiment, the apparatus stores first and secondmathematical equations derived from the insulin action curves. The firstequation expresses remaining insulin action as a function of time afterinjection of a dose of regular insulin. The second equation expressesremaining insulin action as a function of time after injection of a doseof lispro insulin. In this embodiment, the apparatus determines aninsulin action value by determining the time after injection andcalculating the insulin action value using the equation corresponding tothe type of insulin injected.

The preferred embodiment includes a patient-operated apparatus and ahealthcare provider computer in communication with the apparatus. Thisconfiguration of system components is presently preferred for ease ofsetting, storing, and adjusting the target blood glucose value andinsulin sensitivity value of the patient under the supervision of ahealthcare provider. However, those skilled in the art will recognizethat the apparatus itself may also be programmed to adjust the patient'sinsulin sensitivity value based upon the stored blood glucose values andinsulin dose values, eliminating the need for the healthcare providercomputer if physician review is deemed unnecessary.

It is presently preferred to include a blood glucose meter in theapparatus for automated entry of blood glucose values. However, theapparatus need not include a blood glucose meter. In one alternativeembodiment, the blood glucose meter is separate from the apparatus andthe patient manually enters measured blood glucose values into theapparatus through the keypad. In another embodiment, the blood glucosemeter is connectable to the apparatus through a serial input/output portfor automated uploading of the blood glucose values. Similarly, inembodiments of the apparatus which include a modem, the modem need notbe built into the apparatus. In alternative embodiments, the apparatusmay be adapted to receive a separate modem card, as is well known in theart.

Moreover, the apparatus is not limited to storing patient data relatingonly to blood glucose and insulin dose values. In alternativeembodiments, the apparatus also stores guidelines for diet, exercise,and other therapy parameters. Further, the apparatus may be programmedto prompt a patient for data relating to the therapy parameters and todisplay recommended guidelines to the patient.

Additionally, the invention may also be implemented as a simulationsystem for educating and training patients in blood glucose control. Inthe simulation embodiment, the insulin dose values are representative ofsimulated insulin doses and the blood glucose values are representativeof simulated blood glucose concentrations. The patient enters variousinsulin dose values and blood glucose values in the simulation system tolearn their effect on his or her future blood glucose concentration.

Therefore, the scope of the invention should be determined not by theexamples given but by the appended claims and their legal equivalents.

What is claimed is:
 1. An apparatus for assisting a patient havingdiabetes mellitus in controlling blood glucose, said apparatuscomprising: a) an input means for entering a blood glucose valueG(t_(d)) representative of a blood glucose concentration of the patientat time t_(d) and for entering an insulin dose value I_(k)representative of an insulin dose administered to the patient prior totime t_(d); b) a memory means for storing an insulin sensitivity valuerepresentative of an insulin sensitivity of the patient and for storinginformation for determining an insulin action value F_(k)(2^(d))representative of a fraction of insulin action remaining at time t_(d)from said insulin dose; c) a processor connected to said input means andsaid memory means for determining said insulin action value F_(k)(t_(d))and for determining a future blood glucose value G(t_(j)) representativeof an expected blood glucose concentration of the patient at time t_(j),wherein said processor determines said future blood glucose valueG(t_(j)) in dependence upon said blood glucose value G(t_(d)), saidinsulin dose value I_(k), said insulin sensitivity value, and saidinsulin action value F_(k)(t_(d)); d) an interpolation formula tocalculate the insulin action value F_(k)(t_(d)) programmed into theprocessor, the formula to calculate the insulin action value comprisingF _(k)(t _(d))=Y ₀+((Z _(k) −X ₀)(Y ₁ −Y ₀)/(X ₁ −X ₀)) wherein X₀represents an initial insulin dose, Y₀ represents an insulin actionvalue at initial dose X₀, X₁ represents a following insulin dose, Y₁represents an insulin action value at following insulin dose X₁, andZ_(k) represents time after injection of insulin dose I_(k) at timet_(d); e) a formula to calculate the future blood glucose value G(t_(j))programmed into the processor, the formula to calculate the food glucosevalue comprising:${G\left( t_{\quad j} \right)} = {{G\left( t_{d} \right)} - {S\left\lbrack {{\sum\limits_{k = 1}^{N}{I_{k}{F_{k}\left( t_{d} \right)}}} - {F_{k}\left( t_{j} \right)}} \right\rbrack}}$

wherein S represents insulin sensitivity values, I_(k) representsinsulin dose values administered prior to time t_(d), and F_(k)(t_(j))represents insulin action values at time (t_(j)), k=1 represents asingle insulin bolus dose and a supplemental insulin bolus dose, and Nrepresents the total number of insulin bolus doses and supplementalinsulin bolus doses; and f) a display means connected to said processorfor displaying said future blood glucose value G(t_(j)), therebyenabling the patient to take timely corrective action to preventhypoglycemia or hyperglycemia.
 2. The apparatus of claim 1, wherein saidmemory means includes means for storing maximum and minimum valuesdefining a target blood glucose range of the patient, said processorincludes means for determining if said future blood glucose valueG(t_(j)) lies outside of said target range and means for determiningsaid corrective action for the patient when said future blood glucosevalue G(t_(j)) lies outside of said target range, and said display meansincludes means for recommending said corrective action to the patient.3. The apparatus of claim 2, wherein said memory means further includesmeans for storing a target blood glucose value of the patient, saidcorrective action comprises an administration of a supplemental insulindose, and said processor further comprises means for determining saidsupplemental insulin dose in dependence upon said insulin sensitivityvalue and a difference between said future blood glucose value G(t_(j))and said target blood glucose value.
 4. The apparatus of claim 2,wherein said memory means further includes means for storing a targetblood glucose value of the patient, said corrective action comprises aconsumption of a number of grams of carbohydrates, and said processorfurther comprises means for determining said number of grams independence upon a difference between said future blood glucose valueG(t_(j)) and said target blood glucose value.
 5. The apparatus of claim1, wherein said memory means further includes means for storing ahypoglycemic value indicative of a hypoglycemic threshold of thepatient, said processor includes means for determining if said futureblood glucose value G(t_(j)) lies below said hypoglycemic value, andsaid apparatus further comprises audio means connected to aid processorfor audibly alerting the patient when said future blood glucose valueG(t_(j)) lies below said hypoglycemic value.
 6. The apparatus of claim1, wherein said input means comprises a blood glucose measuring meansfor measuring a blood sample of the patient and for producing said bloodglucose value G(t_(d)) from a measurement of said blood sample.
 7. Theapparatus of claim 1, wherein said insulin dose has an insulin type,said input means includes means for entering said insulin type, and saidprocessor includes means for determining said insulin action valueF_(k)(t_(d)) in dependence upon said insulin type.
 8. The apparatus ofclaim 7, wherein said insulin type is selected from the group consistingof regular insulin and lispro insulin.
 9. The apparatus of claim 1,wherein said processor includes means for determining an insulin actionvalue F_(k)(t_(j)) representative of a fraction of insulin actionremaining at time t_(j) from said insulin dose and means for determiningsaid future blood glucose G(t_(j)) in further dependence upon saidinsulin action value F_(k)(t_(j)).
 10. The apparatus of claim 1, whereinsaid processor includes means for determining an ultimate time point atwhich said insulin dose will have no insulin action remaining and meansfor setting time t_(j) equal to said ultimate time point.
 11. Theapparatus of claim 1, wherein said processor includes means fordetermining a plurality of future blood glucose values representative ofa corresponding plurality of expected blood glucose concentrations ofthe patient, and wherein said display means includes means fordisplaying said future blood glucose values in graphical form.
 12. Theapparatus of claim 1, further comprising a communication means connectedto said processor for establishing a communication link between saidapparatus and a healthcare provider computer and for transmitting andreceiving data therebetween.
 13. The apparatus of claim 12, wherein saidcommunication means comprises a modem means for establishing saidcommunication link through a communication network.
 14. The apparatus ofclaim 12, wherein said communication means comprises an input/ outputport for establishing said communication link through a connection cord.15. A system for assisting a patient having diabetes mellitus incontrolling blood glucose, said system comprising: a) an input means forentering a blood glucose value G(t_(d)) representative of a bloodglucose concentration of the patient at time t_(d)and for entering aninsulin dose value I_(k) representative of an insulin dose administeredto the patient prior to time t_(d); b) a memory means for storingmaximum and minimum values defining a target blood glucose range of thepatient, an insulin sensitivity value representative of an insulinsensitivity of the patient, and information for determining an insulinaction value F_(k)(t_(d)) representative of a fraction of insulin actionremaining at time t_(d) from said insulin dose; c) a processor connectedto said input means and said memory means for determining said insulinaction value F_(k)(t_(d)), for determining a future blood glucose valueG(t_(j)) representative of an expected blood glucose concentration ofthe patient at time t_(j), and for determining a corrective action forthe patient when said future blood glucose value G(t_(j)) lies outsideof said target range, wherein said processor determines said futureblood glucose value G(t_(j)) in dependence upon said blood glucose valueG(t_(d)), said insulin dose value, said insulin sensitivity value, andsaid insulin action value F_(k)(t_(d)); and d) an interpolation formulato calculate the insulin action value F_(k)(t_(d)) programmed into theprocessor, the formula to calculate the insulin action value comprising:F _(k)(t _(d))=Y ₀+((Z _(k) −X ₀)(Y ₁ −Y ₀)/(X ₁ −X ₀)) wherein X₀represents an initial insulin dose, Y₀ represents an insulin actionvalue at initial dose X₀, X₁ represents a following insulin dose, Y₁,represents an insulin action value at following insulin dose X₁, andZ_(k) represents time after injection of insulin dose I_(k) at timet_(d); e) a formula to calculate the future blood glucose value G(t_(j))programmed into the processor, the formula to calculate the food glucosevalue comprising.${G\left( t_{\quad j} \right)} = {{G\left( t_{d} \right)} - {S\left\lbrack {{\sum\limits_{k = 1}^{N}{I_{k}{F_{k}\left( t_{d} \right)}}} - {F_{k}\left( t_{j} \right)}} \right\rbrack}}$

wherein S represents insulin sensitivity values, I_(k) representsinsulin dose values administered prior to time t_(d), and F_(k)(t_(j))represents insulin action values at time (t_(j)), k=1 represents asingle insulin bolus dose and a supplemental insulin bolus dose, and Nrepresents the total number of insulin bolus doses and supplementalinsulin bolus doses; and f) a display means connected to said processorfor recommending said corrective action to the patient.
 16. The systemof claim 15, wherein said memory means further includes means forstoring a target blood glucose value of the patient, said correctiveaction comprises an administration of a supplemental insulin dose, andsaid processor further comprises means for determining said supplementalinsulin dose in dependence upon said insulin sensitivity value and adifference between said future blood glucose value G(t_(j)) and saidtarget blood glucose value.
 17. The system of claim 15, wherein saidmemory means further includes means for storing a target blood glucosevalue of the patient, said corrective action comprises a consumption ofa number of grams of carbohydrates, and said processor further comprisesmeans for determining said number of grams in dependence upon adifference between said future blood glucose value G(t_(j)) and saidtarget blood glucose value.
 18. The system of claim 15, wherein saidmemory means further includes means for storing a hypoglycemic valueindicative of a hypoglycemic threshold of the patient, said processorincludes means for determining if said future blood glucose G(t_(j))lies below said hypoglycemic value, and said system further comprisesaudio means connected to said processor for audibly alerting the patientwhen said future blood glucose value G(t_(j)) lies below saidhypoglycemic value.
 19. The system of claim 15, wherein said input meanscomprises a blood glucose measuring means for measuring a blood sampleof the patient and for producing said blood glucose value G(t_(d)) froma measurement of said blood sample.
 20. The system of claim 15, whereinsaid insulin dose has an insulin type, said input means includes meansfor entering said insulin type, and said processor includes means fordetermining said insulin action value F_(k)(t_(d)) in dependence uponsaid insulin type.
 21. The system of claim 20, wherein said insulin typeis selected from the group consisting of regular insulin and lisproinsulin.
 22. The system of claim 15, wherein said processor includesmeans for determining an insulin action value F_(k)(t_(j))representative of a fraction of insulin action remaining at time t_(j)from said insulin dose and means for determining said future bloodglucose value G(t_(j)) in further dependence upon said insulin actionvalue F_(k)(t_(j)).
 23. The system of claim 15, wherein said processorincludes means for determining an ultimate time point at which saidinsulin dose will have no insulin action remaining and means for settingtime t_(j) equal to said ultimate time point.
 24. The system of claim15, wherein said processor includes means for determining a plurality offuture blood glucose values representative of a corresponding pluralityof expected blood glucose concentrations of the patient, and whereinsaid display means includes means for display ing said future bloodglucose values in graphical form.
 25. The system of claim 15, whereinsaid input means includes means for entering a plurality of bloodglucose values and a plurality of insulin dose values, and said systemfurther comprises a computing means in communication with said processorfor receiving said blood glucose values and said insulin dose values andfor calculating from said blood glucose values and said insulin dosevalues an adjusted insulin sensitivity value.
 26. The system of claim25, wherein said input means, said memory means, said processor, andsaid display means are included in a patient-operated apparatus, saidcomputing means comprises a healthcare provider computer, and saidapparatus includes a communication means connected to said processor forestablishing a communication link between said apparatus and saidhealthcare provider computer.
 27. The system of claim 26, wherein saidcommunication means comprises a modem means for establishing saidcommunication link through a communication network.
 28. The system ofclaim 26, wherein said communication means comprises an input/outputport for establishing said communication link through a connection cord.29. A method for assisting a patient having diabetes mellitus incontrolling blood glucose, said method comprising the following steps:a) providing the patient with an apparatus for determining a futureblood glucose value G(t_(j)) representative of an expected blood glucoseconcentration of the patient at time t_(j), wherein said apparatuscomprises a memory, an input means for entering a blood glucose valueG(t_(d)) representative of a blood glucose concentration of the patientat time t_(d) and for entering an insulin dose value representative ofan insulin dose administered to the patient prior to time t_(d), adisplay, and a processor connected to said memory, said input means, andsaid display; b) storing in said memory an insulin sensitivity valuerepresentative of an insulin sensitivity of the patient; c) storing insaid memory information for determining an insulin action valueF_(k)(t_(d)) representative of a fraction of insulin action remaining attime t_(d) from said insulin dose; d) entering in said processor saidinsulin dose value and said blood glucose value G(t_(d)); e) determiningin said processor said insulin action value F_(k)(t_(d)) by programmingthe processor to execute an interpolation formula to calculate theinsulin action value F_(k)(t_(d)) programmed into the processor, theformula to calculate the insulin action value comprising: F _(k)(t_(d))=Y ₀+((Z _(k) −X ₀)(Y ₁ −Y ₀)/(X ₁ −X ₀)) wherein X₀ represents aninitial insulin dose, Y₀ represents an insulin action value at initialdose X₀, X₁ represents a following insulin dose, Y₁ represents aninsulin action value at following insulin dose X₁, and Z_(k) representstime after injection of insulin dose I_(k) at time t_(d); f) determiningin said processor said future blood glucose value G(t_(j)) in dependenceupon said blood glucose value G(t_(d)), said insulin dose value, saidinsulin sensitivity value, and said insulin action value F_(k)(t_(d)) byprogramming the processor to execute a formula to calculate the futureblood glucose value G(t_(j)) programmed into the processor, the formulato calculate the food glucose value comprising:${G\left( t_{\quad j} \right)} = {{G\left( t_{d} \right)} - {S\left\lbrack {{\sum\limits_{k = 1}^{N}{I_{k}{F_{k}\left( t_{d} \right)}}} - {F_{k}\left( t_{j} \right)}} \right\rbrack}}$

wherein S represents insulin sensitivity values, I_(k) representsinsulin dose values administered prior to time t_(d), and F_(k)(t_(j))represents insulin action values at time (t_(j)), k=1 represents asingle insulin bolus dose and a supplemental insulin bolus dose, and Nrepresents the total number of insulin bolus doses and supplementalinsulin bolus doses; and g) displaying said future blood glucose valueG(t_(j)) on said display, thereby enabling the patient to take timelycorrective action to prevent hypoglycemia or hyperglycemia.
 30. Themethod of claim 29, further comprising the step of determining in saidprocessor an insulin action value F_(k)(t_(j)) representative of afraction of insulin action remaining at time t_(j), from said insulindose, and wherein said future blood glucose value G(t_(j)) is determinedin further dependence upon said insulin action value F_(k)(t_(j)). 31.The method of claim 29, wherein the step of determining said futureblood glucose value G(t_(j)) is preceded by the steps of determining insaid processor an ultimate time point at which said insulin dose willhave no insulin action remaining and setting time t_(j) equal to saidultimate time point.
 32. The method of claim 29, further comprising thesteps of determining in said processor a plurality of future bloodglucose values representative of a corresponding plurality of expectedblood glucose concentrations of the patient and displaying said futureblood glucose values in graphical form on said display.
 33. The methodof claim 29, further comprising the steps of storing in said memorymaximum and minimum values defining a target blood glucose range of thepatient, determining in said processor if said future blood glucosevalue G(t_(j)) lies outside of said target range, determining in saidprocessor said corrective action for the patient when said future bloodglucose value G(t_(j)) lies outside of said target range, andrecommending said corrective action on said display.
 34. The method ofclaim 33, wherein said corrective action comprises an administration ofa supplemental insulin dose, and said method further comprises the stepsof storing in said memory a target blood glucose value of the patientand determining in said processor said supplemental insulin dose independence upon said insulin sensitivity value and a difference betweensaid future blood glucose value G(t_(j)) and said target blood glucosevalue.
 35. The method of claim 33, wherein said corrective actioncomprises a consumption of a number of grams of carbohydrates, and saidmethod further comprises the steps of storing in said memory a targetblood glucose value of the patient and determining in said processorsaid number of grams in dependence upon a difference between said futureblood glucose value G(t_(j)).
 36. The method of claim 29, furthercomprising the steps of storing in said memory a hypoglycemic valueindicative of a hypoglycemic threshold of the patient, determining insaid processor if said future blood glucose value G(t_(j)) lies belowsaid hypoglycemic value, and audibly alerting the patient when saidfuture blood glucose value G(t_(j)) lies below said hypoglycemic value.37. The method of claim 29, wherein said input means comprises a bloodglucose meter and the step of entering said blood glucose value G(t_(d))comprises the steps of measuring a blood sample of the patient with saidglucose meter and producing said blood glucose value G(t_(d)) from ameasurement of said blood sample.
 38. The method of claim 29, whereinsaid insulin dose has an insulin type, said method further comprises thestep of entering said insulin type in said processor, and said insulinaction value F_(k)(t_(d)) is determined in dependence upon said insulintype.
 39. The method of claim 38, wherein said insulin type is selectedfrom the group consisting of regular insulin and lispro insulin.
 40. Amethod for assisting a patient having diabetes mellitus in controllingblood glucose, said method comprising the following steps: a) providingthe patient with an apparatus for determining a future blood glucosevalue G(t_(j)) representative of an expected blood glucose concentrationof the patient at time t_(j), wherein said apparatus comprises a memory,an input means for entering a blood glucose value G(t_(d))representative of a blood glucose concentration of the patient at timet_(d) and for entering an insulin dose value representative of aninsulin dose administered to the patient prior to time t_(d), a display,an a processor connected to said memory, said input means, and saiddisplay; b) storing in said memory an insulin sensitivity valuerepresentative of an insulin sensitivity of the patient, information fordetermining an insulin action value F_(k)(t_(d)) representative of afraction of insulin action remaining at time t_(d) from said insulindose, and maximum and minimum values defining a target blood glucoserange of the patient; c) entering in said processor said insulin dosevalue and said blood glucose value G(t_(d)); d) determining in saidprocessor said insulin action value F_(k)(t_(d)) by programming theprocessor to execute an interpolation formula to calculate the insulinaction value F_(k)(t_(d)) as stated in the formula to calculate theinsulin action value comprising:  F _(k)(t_(d))=Y ₀₊((Z _(k−) X ₀)(Y ¹⁻Y ₀)/(X ¹⁻ X ₀)) wherein X₀ represents an initial insulin dose, Y₀represents an insulin action value at initial dose X₀, X₁ represents afollowing insulin dose, Y₁ represents an insulin action value atfollowing insulin dose X₁, and Z_(k) represents time after injection ofinsulin dose I_(k) at time t_(d); e) determining in said processor saidfuture blood glucose value G(t_(j)) by programming the processor toexecute a formula to calculate the future blood glucose value G(t_(j))using the formula to calculate the food glucose value comprising:${G\left( t_{\quad j} \right)} = {{G\left( t_{d} \right)} - {S\left\lbrack {{\sum\limits_{k = 1}^{N}{I_{k}{F_{k}\left( t_{d} \right)}}} - {F_{k}\left( t_{j} \right)}} \right\rbrack}}$

wherein S represents insulin sensitivity values, I_(k) representsinsulin dose values administered prior to time t_(d), and F_(k)(t_(j))represents insulin action values at time (t_(j)), k=1 represents asingle insulin bolus dose and a supplemental insulin bolus dose, and Nrepresents the total number of insulin bolus doses and supplementalinsulin bolus doses, and in dependence upon said blood glucose valueG(t_(d)), said insulin dose value, said insulin sensitivity value, andsaid insulin action value F_(k)(t_(d)); f) determining in said processorif said future blood glucose value G(t_(j)) lies outside of said targetrange; g) determining in said processor a corrective action for thepatient when said future blood glucose value G(t_(j)) lies outside ofsaid target range; and h) recommending said corrective action to thepatient on said display.
 41. The method of claim 40, further comprisingthe step of determining in said processor an insulin action valueF_(k)(t_(j)) representative of a fraction of insulin action remaining attime t_(j) from said insulin dose, and wherein said future blood glucosevalue G(t_(j)) is determined in further dependence upon said insulinaction value F_(k) (t_(j)).
 42. The method of claim 40, wherein the stepof determining said future blood glucose value G(t_(j)) is preceded bythe steps of determining in said processor an ultimate time point atwhich said insulin dose will have no insulin action remaining andsetting time t_(j)equal to said ultimate time point.
 43. The method ofclaim 40, further comprising the steps of determining in said processora plurality of future blood glucose values representative of acorresponding plurality of expected blood glucose concentrations of thepatient and displaying said future blood glucose values in graphicalform on said display.
 44. The method of claim 40, wherein saidcorrective action comprises an administration of a supplemental insulindose, and said method further comprises the steps of storing in saidmemory a target blood glucose value of the patient and determining insaid processor said supplemental insulin dose in dependence upon saidinsulin sensitivity value and a difference between said future bloodglucose value G(t_(j)) and said target blood glucose value.
 45. Themethod of claim 40, wherein said corrective action comprises aconsumption of a number of grams of carbohydrates, and said methodfurther comprises the steps of storing in said memory a target bloodglucose value of the patient and determining in said processor saidnumber of grams in dependence upon a difference between said futureblood glucose value G(t_(j)) and said target blood glucose value. 46.The method of claim 40, further comprising the steps of storing in saidmemory, a hypoglycemic value indicative of a hypoglycemic threshold ofthe patient, determining in said processor if said future blood glucosevalue G(t_(j)) lies below said hypoglycemic value, and audibly alertingthe patient when said future blood glucose value G(t_(j)) lies belowsaid hypoglycemic value.
 47. The method of claim 40, wherein said inputmeans comprises a blood glucose meter and the step of entering saidblood glucose value G(t_(d)) comprises the steps of measuring a bloodsample of the patient with said glucose meter and producing said bloodglucose value G(t_(d)) from a measurement of said blood sample.
 48. Themethod of claim 40, wherein said insulin dose has an insulin type, saidmethod further comprises the steps of entering said insulin type in saidprocessor, and wherein said insulin action value F_(k)(t_(d)) isdetermined in dependence upon said insulin type.
 49. The method of claim48, wherein said insulin type is selected from the group consisting ofregular insulin and lispro insulin.
 50. The method of claim 40, furthercomprising the steps of entering in said processor a plurality of bloodglucose values and a plurality of insulin dose values, determining fromsaid glucose values and said insulin dose values an adjusted insulindose values an adjusted insulin sensitivity value, and storing saidadjusted insulin sensitivity value in said memory.